1. Field of the Invention
The present invention relates to a recording sheet for overhead projectors (OHP) or second original drawing, which is suitable for ink jet recording.
2. Prior Art
Usually, transparent resin films represented by polyester film are used as sheets for OHP. Recording of pictures is made using methods such as handwriting with ink, toner transfer with PPC, heat-sensitive foaming, etc.
Attempts to apply an ink jet recording method to OHP have been made, since it is excellent in distinctness and polychromy of pictures. However, in the case where records are placed on an ordinary film for OHP using an ink jet printer, ample time is required for the ink to dry because the base material has no ink-absorbing ability, and the running, fade-out or uncleaniness of pictures is caused by the ink is not being dried. Also, in the case of polychrome recording, a compound color or bleeding due to the superposition of inks is observed. Further, ink wetting to the surface of the base material is bad, and the inks do not spread out to the desired extent, whereby the apparent density of the ink is held low and recording is poor in practicality.
Therefore, in order to endow ink absorbing and drying abilities, methods of preparing a coated film layer by dispersing organic particles and inorganic particles into a binding agent have been proposed in Japanese Patent Disclosures No. 57-14091, No. 56-99692 and No. 57-107880.
In the above method, however, only a slight improvement has been shown in the ink-absorbing ability or ink-drying ability. The conventional recording sheets have suffered the following disadvantages. Even if they have ink-absorbing abilities to some extent, they are deficient in transparency for OHP use. Also, even if they are excellent in transparency, ink dots do not spread out to the desired extent, whereby an adequate optical density can not be obtained. Even after printing and drying, ink tacks do not disappear, whereby the sheets are easily soiled.